Chapter Heading section layout uses wrong font

I’m using a custom format I’ve used for other projects, and I’m trying to change the font of the chapter heading. The preview in the Section Layouts window looks correct:

but the actual rendered PDF has the wrong font in the chapter heading (presumably the default font):

Any ideas what could be going wrong here? The same thing happened on the front page, seemingly with the same font, but I simply fixed that by explicitly writing the title on the title page instead of using the project title variable (I hope that’s the right word for it).

Does the advice given in this similar thread help? … =2&t=53314

Slàinte mhòr.